Responding to massive public outcry, Yahoo Inc. reversed a decision announced last week to expand its selection of X-rated DVDs and videos sold online. Company officials said Friday that Yahoo!, the world's leading Internet site, had shut its X-rated store and blocked merchants from selling sexually explicit adult-oriented material on its site. The cybergiant also said it will stop accepting classified ads or auction listings for adult items. The move derails Yahoo's longer-term strategy for its adults store to work more closely with merchants and film-production companies in the adult-entertainment industry, plans that have been in the works for 18 months. Yahoo! had made those plans partly because it has been struggling with revenue losses due to a sharp downturn in advertising.